Interactive Transcript
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This is an MRI of the abdomen and
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pelvis in a patient in the early third
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trimester of pregnancy who was referred
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from the maternal fetal medicine clinic
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for an abnormal obstetric ultrasound.
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Again, we've placed our steady-state
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free precession images on the left-hand
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side of the screen and the turbo spin
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echo sequences on the right-hand side.
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We begin to see the gravid uterus and the
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fetus again with a classic T2 heterogeneous
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appearance of the myometrium in both.
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As we scroll inferiorly, we
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have not yet seen the placenta.
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It just starts to come into view here.
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And I want to point out a relatively normal
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relationship between the myometrium and
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the placenta along the superior aspect.
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And so we just see the placenta
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resting against the myometrium.
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It's relatively uniform in thickness and signal.
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And we can see a clear relationship with
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the myometrium with a thick, generous
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amount of overlying muscular tissue.
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As we scroll inferiorly for this patient,
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we start to see some of those classic
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features of placenta accreta spectrum.
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Again, this placenta is low-lying,
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it's lumpy-bumpy, and in this case, we
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see a lot of placental heterogeneity.
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We see very extensive and dark placental bands
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for this patient in addition to some abnormal
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vascularity in the periphery of the placenta.
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Another thing that I want to point out for
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this patient is that if we keep an eye on
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the amount of T2 heterogeneous myometrium
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that's overlying the placenta here.
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As we scroll inferiorly, it becomes really
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difficult to follow the myometrium and
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continue to visualize it as we reach
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these areas where the placenta is bulging
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and lobular and irregular in appearance.
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There's probably a very thin 2 to 3 millimeter
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layer of myometrium present in this patient.
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And we can see that the placenta extends
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fairly far inferiorly in this patient.
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These are coronal T2-weighted images of the
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abdomen and pelvis for the same patient.
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We have a cephalic presentation fetus
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and a low-lying anterior placenta,
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as we saw on the axial images.
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I think the coronal images are very
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demonstrative in this case, as in pointing out
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the irregularity and the abnormal contour of
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this placenta, in addition to the parenchymal
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heterogeneity and all of the abnormal
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vascularity in the periphery of this placenta.
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Again, as we try to follow the
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uterine myometrium, we can trace
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it very clearly, superiorly on the
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steady-state free precession images.
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But as we come inferiorly toward the
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region of this abnormal low-lying
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placenta, the myometrium becomes very
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thin in this region of placental bulge.
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And we see similar findings on
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the turbo spin echo sequences.
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There is marked thinning of the myometrium, and
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in some places, it's difficult to see it at all.
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Finally, these are the sagittal
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steady-state free precession and
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turbo spin echo images for this patient.
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Both are T2-weighted.
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And we can see again this low-lying,
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heterogeneous, lumpy, bumpy placenta
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with multiple placental bands.
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This is probably the largest one.
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There is a placental mass with overlying
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myometrial thinning and occasionally difficult
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to discern the myometrium in this patient.
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The other thing that I'll point out is that in
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this patient, there is a T2 hypointense area
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that is posterior to the placenta and is sitting
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directly on top of the internal cervical os.
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We can also see this triangular area
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where the placenta has separated
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from the underlying myometrium.
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And so in this patient with evidence
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of placenta accreta spectrum, there's
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also a focal placental abruption with
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a fairly large retroplacental hematoma.
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This patient was also taken
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for a cesarean hysterectomy
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with pathology-proven placenta increta.
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And what I'd like to point out is that on
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MRI, we are not able to reliably distinguish
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placenta accreta from placenta increta.
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But what we can say is I see features
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of placenta accreta spectrum without
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evidence of placenta percreta.
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